As is well known, semiconductor electronic devices, e.g. power devices, comprise a small plate of a semiconductor material, known as the “die” or “chip”, which has a surface area of a few square millimeters on which an electronic circuit is monolithically integrated. This die has a plurality of terminals, typically as contact pads (typically formed from metal), which are provided on its surface and which are electrically connected during the manufacturing process to an outer frame, the latter being also made of metal and part of the electronic device.
The electrical connection of the die of semiconductor material to the frame can be achieved by different technologies, including one that provides wire connections and is commonly referred to as the “wire bonding” technique. More particularly, with this technique, one end of each connecting wire is bonded to a contact pad that has been formed on the die of semiconductor material, and the other end is bonded to a corresponding lead formed on the frame to which the die is to be connected.
Electronic power devices are widely used in all branches of electronics. Particularly in the automobile industry, vehicles are equipped with electronic control units containing electronic power devices for controlling the operation of vehicle components. Such control units are becoming more and more compact in size and provide an increasing number of functions. This results in increased power density and consequently an increase in the heat generated from the integrated circuits. More particularly, it has been found that in such cases, wire bonding is inadequate to handle high current densities, referred to as high power hereinafter. The size of the leads employed is on the order of 35 μm, and the lead contacts are not sufficiently reliable to handle currents in excess of a few Amperes.
There is, therefore, a demand for semiconductor electronic devices, especially power devices, which can be operated under extreme conditions, e.g., in environments where wide temperature fluctuations up to 180° C. are expected.
Another demand that comes from the automotive industry, as well as from electronic applications (e.g., printers, interfaces, mobile phones), is for electronic devices that are substantially unaffected by electromagnetic radiation without cumbersome shielding arrangements.